Monday, August 24, 2015

Getting started with Deltang radio control in the garden

Following some discussions on garden railway forums such as the Garden Railway Forum and G Scale Central, I have come to realise that the sheer range and diversity of Deltang radio control equipment can appear quite daunting for those those starting out with radio control. The information on the Deltang website (and to be honest, sometimes in my blog postings) often assumes background knowledge which not everyone possesses. This blog posting (and subsequent posts in this series) aims to demystify the process of getting started with Deltang radio control equipment for garden railway modellers (and maybe others as well).

I have no formal qualifications in electronics but I've been dabbling with Deltang radio control gear for about the past three years and in that time have learned a fair bit - mostly by making and correcting mistakes. Hopefully that will help me to see things from a beginner's perspective. This guide has been checked for accuracy by David Theunissen of Deltang and been given the all clear by a fellow garden railway modeller who was formerly an electrical engineer and is an accomplished electronics hobbyist. Any errors, though, are my own. Hopefully this posting will smooth your passage into making the most of Deltang radio control equipment.

Contents

  • The basic principles of Deltang radio control
  • Binding the receiver to the transmitter
  • Deltang transmitter
  • Deltang receivers
  • Ordering Deltang equipment
  • Examples of locomotives equipped with Deltang receivers

The basic principles of Deltang radio control

Skip this section if you are already au fait with how 2.4gHz radio control equipment works.

The basic components of a traditional radio control system for battery locos are: a transmitter and a receiver connected directly to an Electronic Speed Control (ESC) unit which in turn is connected to the batteries and the motor. When the throttle joystick (or knob) on the transmitter is moved the motor increases in speed.

The Deltang system uses the same principle, but the ESC is combined with the receiver on the same (very small) circuit board.

The receiver/controller can be used with any Spektrum DSM2 transmitter but, to my mind, is most effective when used with one of the purpose-made Deltang transmitters.

For more detailed and generalised information about battery power and radio control see - Getting started with battery power and radio control

Binding

With the 2.4gHz system, a receiver needs to be bound to a particular transmitter.  Once bound, the receiver remembers the settings and does not normally need to bound again - unless you want to bind it to a different transmitter.

When a Deltang receiver is initially turned on, its LED flashes once a second to show it is hunting for the transmitter to which it has been bound. If after about 20 seconds, it has not found its transmitter (or it is new and has not yet been bound), the LED starts flashing rapidly indicating it has now gone into 'bind mode'. To bind it to a Deltang transmitter, the transmitter is turned on while the bind button is being held down.

The LED on the transmitter starts flashing and within a short space of time, the LED on the receiver should begin flashing in unison with it. Shortly afterwards both LEDs stop flashing and remain steady, showing the receiver has been bound to the transmitter and can respond to signals sent from it.

Subsequently, provided its bound transmitter is on, when the receiver is turned on again, its LED will initially flash once a second until it latches on to its transmitter, then the LED will remain on steadily.

See the second part of this video for a demonstration of the bind process with an Rx60 receiver and a Tx22 transmitter:

An unlimited number of receivers can be bound to one transmitter, so several locomotives could be controlled by one transmitter. This means that, provided you only run one loco at a time, you only need one transmitter to control a whole fleet of locos. However, one of the clever features of some Deltang transmitters (eg the Tx22) is their ability to independently control several locomotives at the same time.

Deltang Transmitters

Rather than a joystick, Deltang transmitters have a speed control knob which, under normal circumstances, can be used to control both speed and direction.

Tx20/21

The most basic Deltang transmitter is the Tx20.

This features a speed control knob, a direction switch (which can be used to control accessories if not needed for direction control), two accessory push buttons, a bind button and an on/off switch. Like all Deltang transmitters, it is powered by a PP3 9 volt battery which I find lasts for months.

Normally, the speed control knob controls both speed and direction (centre off, twist one way for forward and the other way for reverse). All Deltang receivers can be purchased and/or re-programmed to operate differently and so, if you want fine control or prefer using a direction switch, then a receiver can be purchased or programmed to use the full length of turn of the speed knob to increase and decrease speed and the switch to change direction. (See How to program Deltang receivers ) and/or see the Variants section in Receivers below for more information).

I have constructed a Tx20 from a kit and described the building process here - How I constructed a Deltang Tx20 transmitter from a kit - pending 

The Tx21 version of this transmitter has a knob in place of the two push buttons. This simulates inertia so when the speed knob is turned, the loco gradually builds up or decreases its speed, the time taken to do this depending on how far the inertia knob has been turned. When the inertia control is set to zero, the loco responds directly to the speed knob.

I have a Tx21 transmitter which I built from a kit. I use this transmitter as a spare, being particularly useful when I have more than one operator.

Tx22

To my mind, the Tx22 is the most versatile of the Deltang transmitters.

In addition to the bind button, on/off button, direction switch and the inertia and speed knobs, the Tx22 has a 12-position selector (Selecta) switch. A different loco can be bound to each of the 12 positions of the Selecta switch (or of course several locos can be bound to each position).

Clicking the Selecta switch to position 1, will put the transmitter in control of whichever loco is bound to position 1. Even if they are switched on, none of the other locos which have been bound to other positions on the Selecta switch will move or change what they are doing. Loco No. 1 could be set in motion and then the switch clicked to position No.3 (say). Loco No. 1 will continue at the same speed while Loco No. 3 is being controlled by the transmitter. Switching back to position 1 will enable the transmitter to gain control of Loco No. 1 again.

Tx22 is the transmitter I use most frequently because I can control all eleven of my battery locos from it (I've not yet converted a twelfth loco to battery power - but it is scheduled)

Deltang Receivers

The sheer range of receivers on the Deltang website can be baffling and slightly mind-blowing at first, so hopefully this section will help you to decide which is most appropriate for you when getting started. Basically, I use only two types of Deltang receiver in locos on my garden railway, depending on the use to which they will be put. There are other receivers which could be used, but for now, let's keep things simple.

Rx60

When I first started using Deltang equipment, the Rx60 was the receiver was the only receiver available which most suited my needs. I have continued to use it and its subsequent variants.

The first thing you notice about the Rx60 is its size - it is tiny when compared to more traditional receivers and ESCs - it measures only 11mm x 22.5mm.

It can cope with 3-13 volts and up to 1.3amps, which is quite adequate for many of the small and not so small locomotives which you may want to run in the garden. Until the introduction of the Rx65 (see below), I used this for all my locos except one, whose motor and gear train meant it sometimes drew over 1.5 amps and so control became somewhat erratic (see Jessie section below).

It in addition to the outputs controlling the motor, it has five additional outputs. Outputs 1 and 2 are pre-programmed to provide automatic directional lighting (1 = forward, 2 = reverse), outputs 3-5 respond to the switches on Deltang transmitters (3 = direction switch left, 4 = direction switch right, 5 = bind button). These outputs can be used for accessories such as interior lighting, or to trigger events on soundcards such as the whistle. I use the bind button on my transmitters to sound the horn or whistle on locos equipped with sound cards (see How to use Deltang receiver output pads).

I have replaced the Rx60 receivers in some of my locos with Rx65 receivers as some larger and heavier loco motors buzzed when when running at slow speed. This has been eliminated completely with the Rx65. (see Sharp Stewart section below)

For more information on ordering specific types of Rx60 receiver see Variants section below.

Rx65

The Rx65 receiver has been developed and produced more recently in response to requests for a more powerful receiver/controller.

As you can see from the photo, it is bigger than the Rx60 (18mm x 35mm) and has a lot more output pads. It is still quite small compared with other rx / ESC systems but has the advantage that the output pads are easier to solder on to. It handles up to 3 amps and 3-18 volts. It can manage up to 6 amps if used with a daughter board, but for now that's beyond the scope of this introductory posting.

The Rx65 has ten outputs, two of which are pre-programmed for direction lighting, the rest responding in different ways to the switches and buttons on Deltang transmitters (see How to use Deltang receiver pads).

Variants

This is an aspect which at first can seem quite baffling for the uninitiated. When ordering Deltang receivers, you need to specify which variation on the basic receiver you require.

The main variants of receivers appropriate for garden railway models are:
  • 1 - responds to the direction switch on the transmitter 
  • 2 - uses the speed control knob to change direction (and speed)
  • 22 - for use with a Tx22 with Selecta switch
With these connectors
  • N - No wires attached
  • W - Tx covered in heat shrink insulation and wires soldered to the power supply and motor terminals
In addition the Rx65 can be supplied with the following connectors
  • R = Red JST plugs for power and motor leads
  • S = Screw terminal for power and motor connections
and/or with a longer aerial 
  • U = long aerial

When ordering you therefore specify the type of variations you require. for example:

Rx65-22-W

would get you an Rx65 receiver, programmed to respond to the Selecta switch on the Tx22, covered in clear heatshrink insulation with the power leads and motor leads already attached

This is the version which I tend to use most frequently now as, although I can solder on my own leads, it's quicker and easier to have a receiver ready to fit.

Whereas:
Rx65-1-SU

would result in an Rx65 receiver, for use with a Tx20/1 transmitter, using the direction switch to change direction,  having a long aerial and with screw terminals for the motor and power supply.

Ordering Deltang equipment

In addition to the suppliers listed on the Deltang website, it is possible to order directly from David at Deltang, by sending him an email specifying your requirements and asking for a PayPal invoice. His email address is - dt AT flyelectric DOT org DOT uk (replacing the AT with @ and the DOTs with full stops). I have found that as soon as I have settled the Paypal invoice during the day, the equipment usually arrives the following day by first class mail.

Examples of locomotives equipped with Deltang receivers.

IP Engineering Lollypop Railcar

This little kit is no longer available from IP Engineering, but I made it to test the feasibility of using Deltang receivers with small, low powered locos.

It is powered by three 1.2v NiMh Low Self Discharge (LSD) batteries which I bought from Hobbyking and uses an Rx60-22-W receiver/controller. As with the majority of my locos, I fit an auto-reset fuse to protect the batteries from accidental short circuit and I use a two way switch to connect the batteries to either the motor or the charge socket, so the batteries can be recharged without having to remove them from the loco.

The charge socket and auto reset fuse are both from Maplin:

 Everything sits loosely inside the body of the railcar. I could have used double-sided sticky pads to fix everything in place, but as I'm always tinkering and experimenting, I like to have the option of easy and quick removal.

I have also made use of output pads 1 and 2 on the receiver to operate directional lighting LEDs in the front and rear lamps (see How to use Deltang receiver pads). For more information about the construction of this railcar see (How I constructed an IP Engineering Lollypop railcar kit).

Sharp Stewart loco No. 5

This was my third scratchbuilt loco, was based on the Southwold Railway loco No. 1, Southwold and made use of a Playmobil 0-4-0 motor block.

There was room inside the main body of the loco for a 12v li-ion CCTV battery pack.

These can be purchased from China through eBay, though these days shipping them to the UK can be problematical as airlines are reluctant to carry li-ion batteries. These batteries include protection circuits against over-discharge and short-circuit and also to monitor charging. Some people are very wary of using li-ion batteries because of their volatility, but I am of the opinion that if you take adequate precautions then the benefits they bring (eg compact size, battery capacity) are worth the added risks.

I included an additional 1.6A auto-reset circuit breaker as added protection. Originally, I used an Rx60 receiver, .....

.... but this has recently replaced with an Rx65b, which cured the buzz made by the motor when running at low speed. The basic circuit for this loco is much the same as for all my locos,

After construction, I added a MyLocoSound steam soundcard to this loco and made use of one of the output pads to sound the whistle when the bind button is pressed on the Tx22 transmitter (see How to use Deltang receiver pads).

For more information on the construction of this locomotive see - How I constructed a Sharp Stewart 2-4-2T locomotive

Peckett Loco No. 1

This was the first UK outline loco which I constructed from a GRS (Garden Railway Specialists) kit, mounted on an LGB ToyTrain 0-4-0 motor block. When I converted it from track-power to battery power, I wanted to make the conversion as quick and easy as I could and so, rather than dismantling the loco to find room for batteries, I placed three 3.7v 18650, lithium-ion batteries in the cab.

 As lithium-ion batteries need a lot more careful management than other types of battery, I wired a them into a battery protection board (purchased on eBay) which protects them against short circuit, over discharge and manages balance charging of the batteries (ie ensuring the batteries are equally charged).

It uses a Deltang Rx65b receiver. The wiring for this loco is slightly more complex than for the previous locos, but the principles are the same.

For more information about the construction and conversion of this loco see - How I constructed a Peckett loco and How I converted a Peckett loco from track power to battery power.

An IP Engineering 'Jessie' diesel locomotive

I have included this loco as it takes a different approach to any of the previous examples. Rather than using an Rx60 or Rx65 receiver/controller, it uses an Rx102 receiver connected to a Brian Jones Mac5 ESC.  The model was made from a kit and has worked its way through four different mechanisms, it now being powered by a USA Trains 0-4-0 motor block.

The original mechanisms in this loco tended to draw more amps than the Rx60 could manage and so, having already got a Mac5 ESC to hand, I opted for the combination of an Rx102-1H receiver connected to it.

It was originally powered by ten 1.2v NiMh batteries, but these have recently been replaced with three 18650 3.7v li-ion batteries and a battery protection board, similar to that used in the Peckett loco above.

I have added a Peter Spoerer / Mtroniks diesel sound card to this loco and use outputs from the receiver to trigger the horn (when the bind button is pressed) and to start and stop the engine sound (using the direction switch) (see How to use Deltang receiver output pads).

Update - 17/9/15
Since writing this entry, I have replaced the above arrangement with a Deltang Rx65b receiver/controller. I have described the installation in detail here - How I installed a Deltang Rx65b in my IP Engineering Jessie



As has been indicated above. I intend to follow-up this blog posting with more postings addressing other aspects of Deltang radio control:
I hope this little introduction to Deltang proves useful. If you have any queries or suggestions for improvements (or spot any ambiguities) then please let me know.

Sunday, August 23, 2015

How I operate some of my points by remote control

The Rationale

When I set up my railway, I naively thought I would be able to operate it from one central position and so made a control panel which was situated in the corner of the leanto. In those early days, my locomotives were all track-powered and controlled by a couple of small LGB transformer controllers.

The trackplan was separated into five electrically isolated sections (switches A - E) and all nine points were operated by point motors using two-way centre-biased switches. There was also a reverse loop operated by a reversing switch.

However, I quickly realised that, not only was following trains around essential when running them in the garden, it was a lot more enjoyable. And so, I invested in various remote control systems using track power, culminating in DCC (see Digital Developments). I was quite satisfied with DCC for several years as it simplified the wiring around the garden (no need for isolated track sections) and I could operate the remote controlled points from the DCC handset. As the wiring to the point motors was already in situ, I placed the the points decoders (and the reverse loop controller) inside the now redundant control panel. This helped protect them from the elements.

Over the past three years, I have steadily experimented-with and ultimately adopted radio control and battery power. I was fed-up with constantly cleaning the track, tracing faulty electrical track joints and having locos grind to a halt when shunting or slow running. My biggest regret, though, was losing the ability to control my awkward-to-reach pointwork remotely from the DCC handset.

On my layout there are six turnouts which are difficult to access, marked in red on this trackplan.


Having sold off my DCC equipment, I ran the railway for a while by operating these points manually. Whilst this was possible, it was quite inconvenient. Most of these points needed to be changed repeatedly during an operating session and bending, reaching and stretching is something which is becoming increasingly difficult as I dodder into old age.

Having become of fan of Deltang radio control equipment for my locos, I was intrigued when David T (Mr Deltang) developed and produced a remote points controller using his 2.4gHz radio control system. It works by controlling servos which can be used to switch the blades of turnouts.

I considered replacing my existing LGB point motors with servos but the logistics of making the transition seemed daunting. For one thing, each servo would need three wires whereas the LGB point motors only require two. This would have entailed running additional wiring around the garden. Also, I was not certain how much the signal wire to each servo would be affected by the long run of wiring from the control box in the leanto to each turnout. The more I thought about it, the more unfeasible it became. "It's a pity the r/c unit couldn't be configured to operate LGB point motors," thought I.

I am in regular correspondence with a fellow garden railway modelling in Australia. Greg Hunter, whose Sandstone & Termite Railway has many similarities with mine, is a dab hand at anything electronic and has produced a series of online articles about using programming Picaxe micro-chips for controlling locos and lineside features. When I explained the situation he immediately concluded that, providing the Deltang receiver could provide binary on/off outputs rather than only servo signals, it would be feasible. The Rx105 receiver used with the unit comes in various configurations (including on/off 'lighting' outputs) and can be re-programmed by the user to provide any combination of outputs - and so  the project looked distinctly doable.

The Transmitter

I sent off for the kit version of the Deltang Tx27 and the Rx105 receiver, which duly arrived (only £22 at the time of writing).

The most difficult stage of making the kit was to drill the holes in the ABS box. I marked these out in a pattern which would loosely represent the relative position of the pointwork on my layout, and drilled the 6mm diameter holes needed for the switches.

The switches were then inserted into the holes and the nuts tightened.

The connections were then wired to the relevant pins on the receiver, following the circuit diagram provided with the kit.

Once all the wiring had been completed, a PP3 battery was connected and the transmitter powered up. There was no way of testing it at that moment, but it seemed to be functioning as expected.

The switching system



The process

  1. When a switch (eg switch 2) is clicked on the the transmitter, a signal is sent to the receiver.
  2. The receiver sends a signal to the Picaxe board (eg input 2)
  3. On receipt of the signal, the Picaxe board checks which way the relevant point (eg Point 2) is already pointing. 
  4. If the point needs reversing, the Picaxe board triggers the reversing relay on the relay board and then triggers the relevant relay (eg Relay 2) to send a 12v pulse to the point motor.

The Relay board

I next turned my attention to constructing the relay board needed to operate the point motors. With Greg's help, we had worked out that we needed six double pole on/off (DPST) relays to operate the six turnouts and a double-pole, double-throw (DPDT) relay to act as a reversing switch to send the point motor one way or the other. Hopefully, this circuit diagram helps explain the relay board's contribution to the system:


The six two pole on-off relays were soldered to a piece of Veroboard in two rows of three, and the DPDT relay beside them.

I tried to ensure that the terminals for the common connections on the relays (such as ground) were soldered to the same rails of the board.

The relays were then wired up - blue wires providing the 12v output to the point motors, the white wires receiving the 5v energising pulses for the relays from the Picaxe board.


The Picaxe-18 Project board was then wired up. The white wires from the point actuating relays were attached to outputs 0-5, and the reversing relay wire was attached to output 7. The white (signal) leads from six servo plugs were attached to inputs 0-2 and 5-7 (3 and 4 are not used for switched inputs) and a 5v voltage regulator with smoothing capacitors was mounted on another piece of Veroboard and connected to the Picaxe board using the 12v supply from an old Scalextric transformer. This also supplies the current needed to switch the point motors.

The 12v supply was then connected to the point actuating relays (the purple wire).

A test program was uploaded to the Picaxe board to check that our logic was correct and the circuitry was given a test run with a spare point motor connected in turn to each of the relay outputs.

The Picaxe was then loaded with the full program and tested, before the assembly was connected to the wiring for the point motors and placed in the control box.

The Picaxe Program

The program for the Picaxe controller uses two main procedures - one to check the initial state of the switches on the transmitter when powered up - and the main, continuously looping procedure which keeps checking for a change in the position of any of the switches on the transmitter.

On power-up the Picaxe checks the existing state of outputs from the receiver and switches each of the relays (and hence the point motors in turn). This ensures that whichever way the switches are pointing on the transmitter, matches the way the points are switched.


Here is the initial checking procedure:

'Program for relay control of point motors using Deltang Tx27 and Rx105-7

'Pin allocation
'pinC.0 input1
'pinC.1 input2
'pinC.2 input3
'pins C.3 and C.4 cannot be used as inputs
'pinC.5 input4
'pinC.6 input5
'pinC.7 input6
'pinB.0 output1
'pinB.1 output2
'pinB.2 output3
'pinB.3 output4
'pinB.4 output5
'pinB.5 output6
'pinB.7 DPDT relay

'ASSUME when input transition is low to high, switch left
'and when input high to low transistion, switch right
'Variables
symbol oldinput1=b6
symbol oldinput2=b7
symbol oldinput3=b8
symbol oldinput4=b9
symbol oldinput5=b10
symbol oldinput6=b11 'the last read state of the input pins

'++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
'This is to set the turnout to the input conditions of the receiver at turnon.
initialize:
'if it's a low input at turn on, switch right.
'if it's high, switch left.

if pinC.0 = 1 then  'checks the input to see if it is high and if so .....
oldinput1 = 1         'stores the state of the switch for future reference
high B.7                 'energises the reversing relay
pause 100
high B.0                 'energises the points relay 1
pause 500               'for half a second
low B.0                  'then turns the relay off
pause 100
low B.7                  'and turns the reversing relay off
else                        'otherwise .....
oldinput1 = 0         'stores the state of the switch
low B.7                  'makes sure the reversing relay is off
pause 100              
high B.0                 'switches on the relay for point 1
pause 500               'for half a second
low B.0                  'then switches it off
endif
.
.
'This procedure is now repeated for each of the inputs and outputs with similar blocks of code
Once the checking procedure has completed, the main procedure is executed. This continually checks the state of the inputs from the receiver (and hence the transmitter) and if it detects a change, it instructs the relevant relay to send a pulse of 12v to the point motor.
start:
'1st relay
if pinC.0 = 1 and oldinput1 = 0 then    'checks if the switch on the tx has moved, if so ...
oldinput1 = 1 'stores the new position of the switch
high B.7                                              'switches on the reversing relay

pause 100                                            'for a second
high B.0                                              'switches on the relay for point 1
pause 500                                            'for half a second
low B.0                                                'switches off relay 1
pause 100
low B.7                                                'switches off the reversing relay
elseif pinC.0 = 0 and oldinput1 = 1 then 'checks if the tx switch is the other way
 oldinput1 = 0
low B.7
pause 100
high B.0
pause 500
low B.0 endif
.
.
'The above block of code is replicated for each of the remaining sets of inputs and outputs.
.

.
goto start
'=======================

And that's basically all there is to it .......


Two of the outputs switch two point motors - the crossover at the back of the garden and the mine link. I have now also fitted a Capacitor Discharge Unit into the 12v supply for the point actuating relays to ensure these motors get the extra kick needed. It wasn't essential, they were switching successfully, but I happened to have a spare left over from my indoor 00 layout.